Electronics and retro homebrew computing

Working on the MPCNC has been a bit of a background project. It’s hard to believe I started printing the parts for it about four months ago. Here is a little about the MPCNC for some context. The project is the brainchild of “Ryan” at v1engineering.com. It is a set of 3D printable part designs, given away freely, and other… Read more »

Five MINI000 boards arrived just after Christmas. Annoyingly I got stung for the import duty, but fair enough. They were still very cheap! The quality looks fantastic, though its hard to tell from a camera-phone shot: The following was done over the course of a few weeks. Unlike the MAXI09 board bringup, I took my time and found I enjoyed… Read more »

I have decided to be a little brave and have opted to build a 68000 SBC instead of one based off a 68008. Specification wise it is similar to the 68020 design: 68000 clocked at 16MHz 1MB static RAM (2 x AS6C4008 (PDF)) 64KB EEPROM (2 x AT28C256 (PDF)) DUART (XR88C681 or, in its place, a SC2681 (PDF))) Expansion connector… Read more »

After writing about building a 68020 computer I feel slightly silly for going back on my word: I have built up a 68008-based computer on breadboard. For one thing going right to a 68020 felt a bit like I’d be missing out; the pleasure is in exploring not the end result. I’d have left out on the other MPUs in… Read more »

My interest in the 68000 family of MPUs stems from two things: it’s use in my all time favourite computer, the Amiga. And the fact that it’s generally considered a very clean design compared to its then main competition. Not that this is a high bar; anything prior to the 386 is dreadful and the later CPUs are not much… Read more »

After pondering on it for a while I’ve concluded that my projects lack variety. I really enjoyed working on the case for MAXI09. The CAD work was interesting and taught me much, and was not just a means to the end of a case for MAXI09. So much so that I want to do more of it. And I want… Read more »

One critical issue arises when attaching mechanical switches, as found in computer keyboards, to digital electronics: switch bounce. When switches are opened and closed, the connection across the switch contacts does not cleanly transition from its previous state to its new state. Instead the switch contacts will (literally) bounce between the old state and new state before finally, after a… Read more »

This is completely “off topic” but worthy of a post. You may have noticed that this blog has been moved off Google’s blogspot platform onto a blog running in WordPress. I’ve never been particularly happy with blogspot. It largely works, but… The big problem (by far) is the post editing control is just awful. Unspeakable bad, in fact. And I… Read more »

It’s been a while since my last post. The main reason being a house move. On the plus side this is good for my projects as I now have lots more room to work on them. On the negative side, at least as far as my hobbies are concerned I’ve, somewhat unexpectedly, found myself doing some work for my old company…. Read more »

Ever since I fired up my first 6809-based computer, I have wondered about the possibility of running programs written in something other then assembly language on it. Not that I don’t love writing code in assembly. But for interests sake, and because it could be a different kind of fun, I’ve been curious about running code written in higher level… Read more »